Primary immunodeficiency often hides in plain sight. Here’s what you need to know.
WHAT IS PRIMARY IMMUNODEFICIENCY?
Primary Immunodeficiency (PI) refers to a group of over 550 rare, chronic disorders in which part of the body’s immune system is missing or doesn’t work correctly. While not contagious, these conditions are caused by hereditary or genetic defects and can affect anyone, regardless of age, gender, or outside factors. While each different disease can vary in symptoms and severity, they all share one common feature—each results from a defect in one of the body's normal immune system functions.
HOW COMMON IS PI?
Primary Immunodeficiency diseases are more prevalent than many realize. According to the Immune Deficiency Foundation (IDF), approximately 500,000 individuals in the U.S. have been diagnosed with a form of PI. However, due to under-diagnosis and misdiagnosis, the actual number of affected individuals is likely higher
“Knowing the signs of PI could’ve saved us years of uncertainty.”
– Caregiver of a PI patient
Further studies estimate that about 1 in 1,200 people in the U.S. are diagnosed with PI, suggesting that many cases remain undetected. This significant diagnostic gap underscores the need for increased awareness and education about PI. Many individuals experience years of unexplained illnesses before receiving an accurate diagnosis. While some forms of PI are identified in infancy, others may not manifest until adolescence or adulthood, making timely recognition and intervention crucial.
HOW IS PI TYPICALLY DIAGNOSED?
Diagnosing PI is often more complex than a single test. It typically involves a combination of medical history, a physical exam, and specialized blood tests to measure immunoglobulin levels and immune system function. In some cases, doctors may also assess how the body responds to vaccines or use genetic testing to identify specific immune defects. These evaluations are usually conducted by a clinical immunologist, a specialist in immune system disorders.
Unfortunately, the path to diagnosis is rarely straightforward. Because the symptoms of PI—like frequent infections or slow healing—can resemble common childhood illnesses, they're often dismissed as regular childhood illness or recurring colds. As a result, it can take years for patients to receive an accurate diagnosis. Studies show the average delay between the onset of symptoms and a confirmed PI diagnosis ranges from 6 to 15 years, leaving individuals vulnerable to ongoing, untreated health complications in the meantime.
LIVING WITH PI
A PI diagnosis can change a person’s life—but it doesn’t define it. With the right treatment, support, and care, many individuals with PI lead full, active lives. From school to sports, careers to friendships, life with PI is about learning to manage challenges while still embracing joy, purpose, and possibility. Early diagnosis and consistent care make a world of difference—and so does a strong community behind you.
Check out stories of individuals facing each day with a PI diagnosis.
WHAT CAN I DO?
You don’t need a anything fancy to make a difference. By learning the signs of PI, sharing this information with others, and supporting ongoing research, you’re helping shorten diagnosis times and strengthen the future for families everywhere. Stay informed, stay involved, and help us spread the sunshine.